One method of reproducing an image in a microfilm image processing apparatus such as a microfilm reader/printer apparatus is what is known as the lens scan method. In this lens scan method, an image-carrying beam of light is directed to a target plane such as the peripheral surface of a photosensitive drum by means of a projection lens which is moved in a direction perpendicular to the lens axis.
In the meantime, there is known a microfilm reader/ printer apparatus of the type equipped with a plurality of projection lenses having different magnification/reduction ratios for reproduction of images. Such plurality of projection lenses are provided to allow formation of images which are magnified or reduced with the ratio available by any selected one of the projection lenses. To exchange one of the lenses with a new one, the lens is moved out of the path of incoming light and the newly selected lens in turn is moved into the path of light. Such exchange of the lenses may be effected either manually or in an automated manner using extra drive means.
A microfilm reader/printer apparatus of the type thus allowing selective use of a plurality of projection lenses may be designed to put the lens scan method into practice for the reproduction of images during printer mode of operation of the apparatus. An example of such a microfilm reader/printer apparatus is disclosed in U.S. Pat. No. 4,666,284. In the microfilm reader/printer apparatus therein taught, a plurality of projection lenses are commonly mounted on a single rotatable turret plate which has different angular positions each having one of the lenses located in line with the path of incoming light. The use of two or more differently designed drive mechanisms is required for the selective use of the projection lenses thus mounted on the turret plate. Provision of such alternative drive mechanisms in the reader/printer apparatus results in extreme complexity of construction of the apparatus.
Furthermore, where an automatic lens exchange mechanism is incorporated in the apparatus to permit automatic exchange of a projection lens system, not only the drive means required for carrying out the lens scan method but extra drive means must be provided for the driving of the lenscarrying turret plate. Provision of such additional drive means results in added complexity of construction of the apparatus.
The present invention contemplates elimination of all these drawbacks of a prior-art microfilm reader or reader/ printer apparatus of the described character.